Version 3 includes two new cases that met our definition from 2020 – far fewer mass shootings than in previous years.
A new variable called “insider/outsider” was added to capture whether the perpetrator had an existing relationship with the site of their shooting. At K-12 schools, 85% of mass shooters were insiders. At colleges and universities it was 89%, and at workplaces it was 91%. At places of worship 36% of shooters were insiders.
In response to a request from a leading gun violence researcher, a new variable coding the nature of psychiatric hospitalization for the 34 perpetrators with that history was added. Under federal law, persons who have been involuntarily hospitalized for psychiatric reasons are permanently barred from gun possession. The data show 88% of hospitalizations were involuntary.
Version 3 also includes a calculation of the years of life lost for each mass shooting victim, based on CDC life expectancy data. Mass shootings have erased a staggering 40,000 years of life since 1966.
You can download the database for free at out website.